Superposition and Coherence & Stationary (Standing) Waves

Question 1

When does Superposition happen?

Answer 1

When two or more waves pass through each other

Question 2

What is the Principle of Superposition?

Answer 2

That when two or more waves cross, the resultant displacement equals the vector sum of the individual displacements

Question 3

What two different types of Interference are there?

Answer 3

Constructive + Destrcutive

Question 4

When two or more waves superpose with each other, the effect is called [………..]

Answer 4

Intereference

Question 5

What happens when two crests interfere?

Answer 5

Gives a bigger crest (Constructive Interference)

Question 6

What does a trough plus a trough give?

Answer 6

Bigger trough (Constructive Interference)

Question 7

What does a crest plus a trough give?

Answer 7

Nothing (Destructive Interference)

Question 8

Which two points with a phase difference of a certain value are in phase?

Answer 8

zero or a MULTIPLE of 360 (degrees) 2π

Question 9

Which two points with a certain phase difference values are exactly out of phase?

Answer 9

Odd-Number multiples of 180 (degrees) π

Question 10

To get interference patterns the two sources must be […………]

Answer 10

coherent

Question 11

What is meant by Coherent Sources?

Answer 11

They have the same wavelength and frequency and a fixed phase difference between them.

Question 12

Constructive or Destructive Interference depends on the [……………….]

Answer 12

path difference

Question 13

What is this term called? ‘The amount by which the path travelled by one wave is longer than the path travellled by the other wave’

Answer 13

Path Difference

Question 14

What is the Constructive Interference Path Difference?

Answer 14

n λ (where n is an integer)

Question 15

What is the Destructive Interference Path Difference?

Answer 15

(n + 0.5) λ

Question 16

Show the apparatus used the observe interference with sound waves.

Answer 16

Question 17

Describe how you can observe interference with sound waves.

Answer 17

• Connect speakers to the same oscillator and place them in line with each other
• Walk slowly across the room in front of them
• You will hear varying volumes of sound. At the points where the sound is loudest, the path difference is a whole wavelength
• The sound will be quietest at points where the path difference is an odd number of half wavelengths

Question 18

Diagram showing waves in phase.

Answer 18

Question 19

Are points A and B in phase on the diagram?

Answer 19

YES

Question 20

Are points A and C in or Out of Phase?

Answer 20

Out of Phase

Question 21

When do you get Stationary Waves?

Answer 21

When a Progressive Wave is Reflected at a Boundary

Question 22

What is the PROPER definition of a Stationary Wave?

Answer 22

A stationary wave is a superposition of two progressive waves with the same wavelength, moving in opposite directions

Question 23

Is energy transferred in a Stationary Wave?

Answer 23

No energy is transferred

Question 24

What are Nodes?

Answer 24

where the amplitude of the vibration is zero

Question 25

What are AntiNodes?

Answer 25

Are points of maximum amplitude